500 kV CVT电压异常分析与处理

Analysis and Treatment on Abnormal Voltage Issue of 500 kV CVT

本文介绍了一起500 kV电容式电压互感器二次电压值偏高的异常故障,依据其结构特点、电气原理、电容量及介损试验,初步判断是由电容式电压互感器6-8只高压电容元件击穿引起。对该设备解体检查分析,发现7只高压电容元件击穿,且其铝箔表面有压痕褶皱现象,推断制造过程中存在工艺问题。验证了理论计算的正确性,找出了设备故障所在。推导了电容元件击穿数量与二次输出电压变化率的映射,设定了预警值,并结合运行经验,对设备供货方、运维方提出预防建议,以保障设备安全稳定运行。

The abnormal fault of high secondary voltage of 500 kV capacitor voltage transformer is introduced in this paper.It is judged preliminarily on the basis of the structural characteristics,electrical principles,capacitance and dielectric loss test of the capacitor voltage transformer that the fault is due to breakdown of 6~8 pieces of high-voltage capacitor elements of the capacitor voltage transformer.It is found throughout disassembly,inspection and analysis of the equipment that 7 pieces of high-voltage capacitor elements are breakdown and the surface of the aluminum foil has indentation and wrinkle.It is inferred that there are process issues during manufacturing process.The correctness of the theoretical calculation is verified and the fault of the equipment is found out.The mapping of the number of capacitor element breakdowns and the variation rate of secondary output voltage is derived and a warning value is set.The preventive sugegstions for the equipment supplier and operation as well as maintenance side are posposed with combination of operation experience so to assure safe and stable operation of the equipment.